1. Field of the Invention
The present invention relates to pipe lining techniques, and more particularly to a pipe liner bag, a manufacturing method therefor, and a pipe repair method which is conducted by using the pipe liner bag.
2. Description of the Related Art
When an underground pipe, such as pipelines and passageways, becomes defective or too old to perform properly, the pipe is repaired and rehabilitated without digging the earth to expose the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering. Typically, the method is disclosed by Japanese Provisional Patent Publication (Kokai) No. 60-242038.
According to the method described in the above-mentioned publication, the pipe repair method comprises inserting a sufficiently long tubular flexible liner bag into the pipe to be repaired by means of a pressurized fluid, like air and water. The tubular liner bag is made of a flexible resin-absorbent material impregnated with a thermosetting resin, and has the outer surface covered with an impermeable plastic film.
More particularly, according to the publication, the tubular flexible liner bag is closed at one end and open at the other; the tubular flexible liner bag is first flattened, then, the closed end of the tubular liner bag is tied to a control rope; the open end of the tubular liner bag is made to gape wide and hooked (anchored) at the end of the defective or old pipe in a manner such that the wide-opened end of the liner completely and fixedly covers and closes the pipe end; a portion of the liner is pushed into the pipe; then, the pressurized fluid is applied to the said portion of the tubular liner such that the fluid urges the tubular liner to enter the pipe. Since one end of the tubular liner is hooked at the end of the pipe, it remains there while the rest of the flexible liner bag is turned inside out as it proceeds deeper in the pipe. (Hereinafter, this manner of procedure shall be called "everting".) When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the control rope holds the closed end of the tubular liner bag to thereby control the length of the tubular liner in the pipe. Then, the everted tubular liner is pressed against the inner wall of the pipe by the said pressurized fluid, and the tubular flexible liner is hardened as the thermosetting resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag by means of a hot steam, etc. It is thus possible to line the inside wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
However, the above-mentioned method, if applied to an underground pipe into which ground water penetrates, gives rise to a problem that the thermosetting resin impregnated in the pipe liner bag get in touch with the ground water to cause the thermosetting resin to be incompletely cured.
To solve the above problem, a method of lining a pipe using a multi-layer pipe liner bag has been proposed. A multi-layer liner bag for this method is shown in FIG. 7. Each of layers of the liner bag is impregnated with a hardenable resin or a grout material such that a layer impregnated with the grout material is pressed against the inner wall of a pipe to be repaired when the pipe liner bag is everted and inserted into the pipe.
According to the above-mentioned method, the grout material impregnated in the outermost layer, which can get in touch with ground water, is cured if touching ground water or the like, the hardenable resin impregnated in inner layers is protected from incomplete curing possibly caused by ground water, thus enabling an underground pipe or the like, into which ground water penetrates, to be favorably lined with the hardenable resin.
However, since the grout material and hardenable resin are generally different in category, a flange portion 112a of a branch pipe liner bag 112 for lining a branch pipe 111 is not integrated with a pipe liner bag 101, as shown in FIG. 7. Further, if a barrier film or the like intervenes between the flange portion 112a of the branch pipe liner bag 112 and the pipe liner bag 101, the flange portion 112a and the pipe liner bag 101 is not integrated.